There is one free programme called imageJ that would allow you to carry out all kinds of IF analysis. The thing is that you need to download suitable add-ins that fits the nature of your analysis. Alternatively try FIJI which is essentially ImageJ but coming with most popular add-ins.
Any other IF analytical softwares will just cost you a fortune.
I am not sure what kind of analysis you need to do, but I would strongly recommend you try MIPAR at www.MIPAR.us.
It is very powerful and intuitive 2D/3D image analysis software which is being released as a free beta trial in two weeks. It offers segmentation and analysis tools I have not seen in any other package and is designed by actual end-users. You can sign up on the site and even submit a test image to see if it can help.